I built khata for my sister: the household ledger that reads your payment messages

Description and use

Khata is a privacy‑preserving, zero‑login household ledger that parses payment messages, computes the minimal set of transfers, and seals all entries for auditability.

Problem

Shared households struggle to track who paid what for bills, leading to arguments over who owes whom.

Outcome

Khata provides a privacy‑preserving, zero‑login household ledger that automatically parses payment messages, calculates the fewest transfers, and seals all data for verifiable audit.

Workflow

• Paste chat conversation into the web app
• Khata parses each message, extracting fields with confidence scores
• The app displays parsed entries and highlights unparseable lines
• Users review and confirm entries
• Khata computes the minimal settlement plan using the largest‑remainder method
• The plan is shown with transfer details
• All entries and the plan are sealed with SHA‑384 hashes
• Users can export or audit the sealed ledger

Evidence

khata reads the messages a shared home actually produces — a UPI SMS, a WhatsApp forward, the note on the back of a receipt — turns them into a real ledger, keeps the original text as evidence, works out the shortest way to settle up, and seals every change so the number can be checked instead of believed.

Source

The app never depends on it. A deterministic rule engine reads every message instantly, with no download and no network, and reports its confidence per field.

Source

One pure function, analyseSettlement, behind the page, the REST route and the agent tool. Splits use the largest‑remainder method, so three ways always sums to the whole exactly — no stray paise to argue about.

Source

Per line, a chain of SHA‑384( UTF‑8(prevSeal) || canonicalJson(event) )… Delete a line and the row is kept as a tombstone, so "it existed and was removed" stays provable.

Source